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authorTushar Dave <tushar.n.dave@intel.com>2012-07-12 08:56:56 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-07-19 08:58:57 -0700
commit3cc4e0e187e4187a6ec13a79dafc1b0f72e31afa (patch)
treee3e02e5c32ed8b87d6f04f335b01815fbfebaa0a
parenta3c021d25debc6278951e0112b1a06d8b7376d22 (diff)
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e1000e: Correct link check logic for 82571 serdes
commit d0efa8f23a644f7cb7d1f8e78dd9a223efa412a3 upstream. SYNCH bit and IV bit of RXCW register are sticky. Before examining these bits, RXCW should be read twice to filter out one-time false events and have correct values for these bits. Incorrect values of these bits in link check logic can cause weird link stability issues if auto-negotiation fails. Reported-by: Dean Nelson <dnelson@redhat.com> Signed-off-by: Tushar Dave <tushar.n.dave@intel.com> Reviewed-by: Bruce Allan <bruce.w.allan@intel.com> Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/net/ethernet/intel/e1000e/82571.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/net/ethernet/intel/e1000e/82571.c b/drivers/net/ethernet/intel/e1000e/82571.c
index c6d95f2031e..a9dd6a92cf5 100644
--- a/drivers/net/ethernet/intel/e1000e/82571.c
+++ b/drivers/net/ethernet/intel/e1000e/82571.c
@@ -1553,6 +1553,9 @@ static s32 e1000_check_for_serdes_link_82571(struct e1000_hw *hw)
ctrl = er32(CTRL);
status = er32(STATUS);
rxcw = er32(RXCW);
+ /* SYNCH bit and IV bit are sticky */
+ udelay(10);
+ rxcw = er32(RXCW);
if ((rxcw & E1000_RXCW_SYNCH) && !(rxcw & E1000_RXCW_IV)) {